A keyboard is one of the widely-used computer peripheral devices. Via the keyboard, the user may input characters or commands into a computer. FIG. 1 is a schematic top view illustrating the outward appearance of a conventional keyboard. The surface of the conventional keyboard 1 includes plural keys 10. These keys 10 are classified into several types, e.g. ordinary keys 101, numeric keys 102 and function keys 103. When one or more keys are depressed by a user, a corresponding signal is issued to the computer, and thus the computer executes a function corresponding to the depressed key or keys. For example, when an ordinary key 101 is depressed, a corresponding English letter or symbol is inputted into the computer. When a numeric key 102 is depressed, a corresponding number is inputted into the computer. In addition, the function keys 102 (F1˜F12) can be programmed to cause corresponding application programs to provide certain functions.
With the maturity of the computing technologies, the conventional keyboard that has basic functions fails to meet the requirements of various users. For this reason, the keyboard manufacturers make efforts in designing novel keyboards with diversified functions. Recently, an illuminated keyboard with a luminous function has been disclosed. Since the outward appearance of the conventional illuminated keyboard is similar to the outward appearance of the conventional keyboard 1, only the inner structure of the conventional illuminated keyboard will be illustrated in more details as follows.
FIG. 2 is a schematic cross-sectional view illustrating a conventional illuminated keyboard. As shown in FIG. 2, the illuminated keyboard 2 comprises plural keys 20, a membrane switch circuit member 21, a light guide plate 22, an illumination module 23, a main circuit board 24, a reflector 25 and a base plate 26. Each of the keys 20 comprises a keycap 201, a key housing 202 and an elastic element 203. From top to bottom, the keycap 201, the key housing 202, the elastic element 203, the membrane switch circuit member 21, the light guide plate 22, the reflector 25 and the base plate 26 of the conventional illuminated keyboard 2 are sequentially shown. The main circuit board 24 is located at a side of the membrane switch circuit member 21. The illumination module 23 is located at another side of the membrane switch circuit member 21. The conventional illuminated keyboard 2 is a keyboard for a desktop computer.
In the key 20, the keycap 201 is exposed outside the surface of the conventional illuminated keyboard 2, so that the keycap 201 can be depressed by the user. The key housing 202 is used for fixing the keycap 201 and the elastic element 203. The elastic element 203 is penetrated through the key housing 202. In addition, both ends of the elastic element 203 are in contact with the keycap 201 and the membrane switch circuit member 21, respectively.
The membrane switch circuit module 21 comprises an upper wiring board 211, a partition plate 212 and a lower wiring board 213. The upper wiring board 211, the partition plate 212 and the lower wiring board 213 are all made of a transparent material. The transparent material includes for example polycarbonate (PC) or polyethylene (PE). The upper wiring board 211 has plural upper contacts 2111. The partition plate 212 is disposed under the upper wiring board 211, and comprises plural partition plate openings 2121 corresponding to the plural upper contacts 2111. The lower wiring board 213 is disposed under the partition plate 212, and comprises plural lower contacts 2131 corresponding to the plural upper contacts 2111. The plural lower contacts 2131 and the plural upper contacts 2111 are collaboratively defined as plural key intersections. Moreover, the membrane switch circuit module 21 is connected with the main circuit board 24 for transmitting electric power and signals.
The illumination module 23 comprises an illumination circuit board 231 and plural light emitting diodes 232. For clarification and brevity, only a light emitting diode 232 is shown in the drawing. The illumination circuit board 231 is located at the first side of the membrane switch circuit member 21 for providing another electric power to the plural light emitting diodes 232. The plural light emitting diodes 232 are disposed on the illumination circuit board 231. By acquiring the electric power from the illumination circuit board 231, the plural light emitting diodes 232 are enabled to emit plural light beams. Generally, the plural light emitting diodes 232 are side-view light emitting diodes. By the light guide plate 22, the plural light beams are guided to the keycaps 201. As shown in FIG. 2, the reflector 25 is disposed under the light guide plate 22 for reflecting the plural light beams. The base plate 26 is disposed under the reflector 25 for supporting the keycap 201, the key housing 202, the elastic element 203, the membrane switch circuit member 21, the light guide plate 22 and the reflector 25.
In the conventional illuminated keyboard 2, the keycap 201 has a light-transmissible region 2011. The light-transmissible region 2011 is located at a letter region or a symbol region of the keycap 201. Moreover, the position of the light-transmissible region 2011 is aligned with a corresponding light-guiding zone 221 of the light guide plate 22. In such way, the light beams can be guided to the light-transmissible region 2011 through the light-guiding dots 2211 of the light-guiding zone 221, thereby illuminating the letter region or the symbol region of the keycap 201. Consequently, the illuminating efficacy is achieved.
Hereinafter, the inner structure of another conventional illuminated keyboard will be illustrated with reference to FIG. 3. FIG. 3 is a schematic cross-sectional view illustrating another conventional illuminated keyboard. As shown in FIG. 3, the illuminated keyboard 3 comprises plural keys 30, a membrane switch circuit member 31, an illumination module 32, a main circuit board 33, a light guide plate 34, a reflector 35 and a base plate 36. Each of the keys 30 comprises a keycap 301, a scissors-type connecting element 302 and an elastic element 303. From top to bottom, the keycap 301, the scissors-type connecting element 302, the elastic element 303, the membrane switch circuit member 31, the light guide plate 34, the reflector 35 and the base plate 36 of the illuminated keyboard 3 are sequentially shown. The illumination module 32 is located at a first side of the membrane switch circuit member 31. The main circuit board 33 is located at a second side of the membrane switch circuit member 31. Except that the key housing 202 of the illuminated keyboard 2 of FIG. 2 is replaced by the of the scissors-type connecting element 302 of the illuminated keyboard 3, the structures and functions of other components of the illuminated keyboard 3 are similar to those of the illuminated keyboard 2, and are not redundantly described herein.
However, the conventional illuminated keyboard still has some drawbacks. For example, in the conventional illuminated keyboard, the light guide plate is necessary for guiding the light beams to illuminate the keys. Since the light guide plate has plural light-guiding dots for guiding the light beams and the key layout configurations of different illuminated keyboards are not all identical, the distribution profile of the light-guiding dots of the light guide plate should be correspondingly adjusted. As known, since it is troublesome to adjust the distribution profile of the light-guiding dots, the fabricating cost will be increased. Moreover, in a case that the illuminated keyboard comprises a scissors-type connecting element, it is necessary to additionally break holes through the light guide plate to combine the scissors-type connecting element and the light guide plate together. That is, the fabricating cost is also increased. Moreover, the use of the light guide plate increases the overall volume of the keyboard and is detrimental to the slimness of the keyboard.
Therefore, there is a need of providing an improved illuminated keyboard so as to obviate the above drawbacks.